Measurement of Protein Synthesis Rate in Rat by [11C]Leucine PET Imaging: Application to the TgF344-AD Model of Alzheimer's Disease.

Long-term memory requires stable protein synthesis and is altered in Alzheimer's disease (AD). This study aimed to implement a method to measure the cerebral protein synthesis rate (PSR) with [11C]leucine PET in vivo in rats and evaluate potential PSR alterations longitudinally (6, 12 and 18 months old) in the TgF344-AD rat model of AD. Wistar, wild-type (WT) and TgF344-AD rats (TG) were scanned for 60 min with [11C]leucine. Arterial blood activity was monitored online and with discrete whole blood and plasma samples by γ-counting in Wistar rats, WT (n = 4) and TG (n = 5). Unlabelled amino acids were measured in plasma. The sensitivity of [11C]leucine PET to measure alterations in PSR was assessed in Wistar rats by injection of PSR inhibitor anisomycin before PET acquisition. Anisomycin administration significantly reduced the net uptake rate constant (Kcplx) of [11C]leucine and PSR, proving the suitability of the method. For the longitudinal study, averaged population-based input functions were used to calculate PSR. We found a significant genotype effect on PSR (decrease in TG vs WT) only in the globus pallidus. This study suggests that [11C]leucine PET is sensitive enough to measure brain PSR in rat but that cross-sectional design with individual input function should be preferred.

Amphiphilic nanoparticles generate curvature in lipid membranes and shape liposome-liposome interfaces.

We show by molecular dynamics that amphiphilic Au nanoparticles (NP) with a diameter of 4 nm generate curvature in phosphatidylcholine lipid membranes. NPs generate negative curvature when they adsorb on the membrane surface but, as they get spontaneously and progressively embedded into the membrane core, the curvature turns positive. As membrane embedding is kinetically slow, both configurations can be observed by Cryo-EM. NP-induced curvature explains the peculiar structure of liposome-liposome interfaces in presence of NPs.

Effects of three husbandry systems on health, welfare and productivity of organic pigs.

Organic pig husbandry systems in Europe are diverse - ranging from indoor systems with concrete outside run (IN) to outdoor systems all year round (OUT) and combinations of both on one farm (POUT). As this diversity has rarely been taken into account in research projects on organic pig production, the aim of this study was to assess and compare pig health, welfare and productivity in these three systems. Animal health and welfare were assessed using direct observation and records of 22 animal-based measures, comprising 17 health-, 3 productivity- and 2 behavioural measures. These were collected in pregnant sows, weaners and fattening pigs during direct observations and from records within a cross-sectional study on 74 farms (IN: n = 34, POUT: n = 28, OUT: n = 12) in eight countries. Overall, prevalence of several animal health and welfare issues was low (e.g. median 0% for pigs needing hospitalisation, shoulder lesions, ectoparasites; <5% for runts, tail lesions, conjunctivitis). Exceptions in particular systems were respiratory problems in weaners and fatteners (IN: 60.0%, 66.7%; POUT: 66.7%, 60.0%), weaning diarrhoea (IN: 25.0%), and short tails in fatteners (IN: 6.5%, POUT: 2.3%). Total suckling piglet losses (recorded over a period of 12 months per farm) were high in all three systems (IN: 21.3%; POUT: 21.6; OUT: 19.2%). OUT had lower prevalences of respiratory problems, diarrhoea and lameness of sows. POUT farms in most cases kept sows outdoors and weaners and fatteners similar to IN farms, which was reflected in the results regarding several health and welfare parameters. It can be concluded, that European organic pigs kept in all three types of husbandry system showed a low prevalence of health and welfare problems as assessed by our methodology, but respiratory health and diarrhoea should be improved in weaners and fatteners kept indoors and total piglet mortality in all systems. The results provide benchmarks for organic pig producers and organisations which can be used in strategies to promote health and welfare improvement. Furthermore, in future research, the identified health and welfare issues (e.g. suckling piglet mortality, weaning diarrhoea) should be addressed, specifically considering effects of husbandry systems.

Interaction of hydrophobic polymers with model lipid bilayers.

The interaction of nanoscale synthetic materials with cell membranes is one of the key steps determining nanomaterials' toxicity. Here we use molecular simulations, with atomistic and coarse-grained resolution, to investigate the interaction of three hydrophobic polymers with model lipid membranes. Polymer nanoparticles made of polyethylene (PE), polypropylene (PP) and polystyrene with size up to 7 nm enter easily POPC lipid membranes, localizing to the membrane hydrophobic core. For all three materials, solid polymeric nanoparticles become essentially liquid within the membrane at room temperature. Still, their behavior in the membrane core is not the same: PP and PS disperse in the core of the bilayer, while PE shows a tendency to aggregate. We also examined the interaction of the polymers with heterogeneous membranes, consisting of a ternary lipid mixture exhibiting liquid-ordered/liquid-disordered phase separation. The behavior of the three polymers is markedly different: PP disfavors lipid phase separation, PS stabilizes it, and PE modifies the topology of the phase boundaries and causes cholesterol depletion from the liquid ordered phase. Our results show that different hydrophobic polymers have major effects on the properties of lipid membranes, calling for further investigations on model systems and cell membranes.

Computation of shear viscosity of colloidal suspensions by SRD-MD.

The behaviour of sheared colloidal suspensions with full hydrodynamic interactions (HIs) is numerically studied. To this end, we use the hybrid stochastic rotation dynamics-molecular dynamics (SRD-MD) method. The shear viscosity of colloidal suspensions is computed for different volume fractions, both for dilute and concentrated cases. We verify that HIs help in the collisions and the streaming of colloidal particles, thereby increasing the overall shear viscosity of the suspension. Our results show a good agreement with known experimental, theoretical, and numerical studies. This work demonstrates the ability of SRD-MD to successfully simulate transport coefficients that require correct modelling of HIs.

Selective mobilization of fatty acids in adipose tissue of heavy pigs.

The mobilization of fatty acids during food deprivation is a selective process studied in different species (humans, rodents, birds, viverrids). The aim of this work was to study the effect of fasting on selective mobilization in commercial pigs. A total of 16 barrows (Large White×Landrace (167 kg±12.5 kg live weight) were subdivided into two homogeneous groups, one subjected to 12 h and the other to 60 h of fasting (fasting time) before slaughtering. For each pig inner and outer backfat layer were sampled at slaughter and at ham trimming 24 h later (sampling time). Increasing the fasting time and the sampling time after slaughter caused an increase in the amount of free fatty acids in both layers. Therefore it can be argued that during fasting lipolysis is stimulated and remains active also after slaughtering. The factors that stimulate lipolysis determine a greater mobilization of unsaturated fatty acids than saturated ones. Thus fasting time may influence the suitability of pork for processing and conservation, since free fatty acids are more suitable for oxidation than the esterified ones.

Study of the B1-B2 transition in colloidal clusters.

The possible mechanisms for the B1 (NaCl-type) to B2 (CsCl-type) transition in crystalline colloidal clusters of equally sized particles are studied by means of two computational techniques: metadynamics and nudged elastic band calculations. The system is modelled by a screened Coulomb potential. Different interaction ranges are considered. The transition from a perfect NaCl cubic cluster to a full CsCl cluster is forced by metadynamics, revealing a transition path with intermediate metastable configurations in which planes are shifted one by one. The presence of metastable configurations in the transition path, corresponding to a certain number of NaCl planes turned into CsCl, has clear analogies with the known Hyde and O'Keeffe mechanism for ionic crystals, with some important differences due to finite-size effects. These comprise the fact that the transition starts by shifting a surface plane by means of a row-by-row mechanism that has no analog in bulk crystals. The energy barriers between the local minima in the transition path are calculated, showing that the barriers strongly depend on the screening length, in such a way that the B1 metastable phase can have very long lifetimes when the interaction is sufficiently long-ranged.

Aggregation in colloidal suspensions: evaluation of the role of hydrodynamic interactions by means of numerical simulations.

Numerical simulations constitute a precious tool for understanding the role of key parameters influencing the colloidal arrangement in suspensions, which is crucial for many applications. The present paper investigates numerically the role of hydrodynamic interactions on the aggregation processes in colloidal suspensions. Three simulation techniques are used: Brownian dynamics without hydrodynamic interactions, Brownian dynamics including some of the hydrodynamic interactions, using the Yamakawa-Rotne-Prager tensor, and stochastic rotation dynamics coupled with molecular dynamics. A system of monodisperse colloids strongly interacting through a generalized Lennard-Jones potential is studied for a colloid volume fraction ranging from 2.5 to 20%. Interestingly, effects of the hydrodynamic interactions are shown in the details of the aggregation processes. It is observed that the hydrodynamic interactions slow down the aggregation kinetics in the initial nucleation stage, while they speed up the next cluster coalescence stage. It is shown that the latter is due to an enhanced cluster diffusion in the simulations including hydrodynamic interactions. The higher the colloid volume fraction, the more pronounced the effects on the aggregation kinetics. It is also observed that hydrodynamic interactions slow down the reorganization kinetics. It turns out that the Brownian dynamics technique using the Yamakawa-Rotne-Prager tensor tends to overestimate the effects on cluster diffusion and cluster reorganization, even if it can be a method of choice for very dilute suspensions.

Kinetically driven ordered phase formation in binary colloidal crystals.

The aggregation of binary colloids of the same size and balanced charges is studied by Brownian dynamics simulations for dilute suspensions. It is shown that, under appropriate conditions, the formation of colloidal crystals is dominated by kinetic effects leading to the growth of well-ordered crystallites of the sodium-chloride (NaCl) bulk phase. These crystallites form with very high probability even when the cesium-chloride (CsCl) phase is more stable thermodynamically. Global optimization searches show that this result is not related to the most favorable structures of small clusters, which are either amorphous or of the CsCl structure. The formation of the NaCl phase is related to the specific kinetics of the crystallization process, which takes place by a two-step mechanism. In this mechanism, dense fluid aggregates form at first and then crystallization follows. It is shown that the type of short-range order in these dense fluid aggregates determines which phase is finally formed in the crystallites. The role of hydrodynamic effects in the aggregation process is analyzed by stochastic rotation dynamics - molecular dynamics simulations, and we find that these effects do not play a major role in the formation of the crystallites.

Aggregation kinetics and gel formation in modestly concentrated suspensions of oppositely charged model ceramic colloids: a numerical study.

Aggregation kinetics and gel formation in aqueous suspensions that undergo heteroaggregation are studied by means of Brownian dynamics simulations. The simulated system, described in a previous paper [M. A. Piechowiak, A. Videcoq, F. Rossignol, C. Pagnoux, C. Carrion, M. Cerbelaud, R. Ferrando, Langmuir, 2010, 26(15), 12540-12547.], is constituted of two kinds of synthesized, almost equally sized colloids: silica particles that are negatively charged and alumina-coated silica particles that are positively charged. The interactions between colloids are modeled by the DLVO potential. Several compositions are analyzed, from silica-rich to alumina-rich cases. The particle volume fraction φ is varied in the range 6-12%. The study of the aggregation kinetics allows us to clarify the effect of those variations on the clustering process. Gelation is analyzed by detection of spanning clusters in each x-, y-, z-direction of the cubic simulation box. Percolating networks start to be observed from φ = 7%, a low value of the volume fraction close to the solid volume fraction experimentally measured in sediments of those suspensions.

Performance and fat quality of heavy pigs fed maize differing in linoleic acid content.

Maize shows wide differences in linoleic acid due both to total lipid content and to fatty acid profile. Therefore, diets containing the same high maize percentage (up to 55%) can differ in linoleic acid content and lead to subcutaneous fats of differing suitability for raw ham curing. Two trials were performed on heavy pigs; in the first, 60 pigs (body weight 48.7+/-5.1 kg) were fed three diets made using three maize batches differing in linoleic acid due to different total lipid content, in the second trial, 40 pigs (live weight 70.4+/-3.4 kg) were fed two diets made using two maize batches differing in linoleic acid due to their fatty acid profile. Pigs were slaughtered at 170 kg of live weight. In both trials, the growth and slaughtering performance did not differ. In the first trial the three diets lead to a different content of linoleic acid both in subcutaneous (low linoleic vs medium linoleic vs high linoleic P0.01) and intramuscular fat (low linoleic vs high linoleic P0.05). In the second trial different linoleic acid content was observed for subcutaneous fat (P0.01) but not for intramuscular fat. To formulate diets for heavy pigs, it is crucial to know the linoleic acid content of the maize used, because differences of only 0.3% can lead to significant differences in fatty acids composition of depot fats.

Use of pure glycerol in fattening heavy pigs.

Eighty Italian Duroc×Italian Large White pigs (BW 42.6±3.37kg) were used to determine the effects of pure glycerol on growth performance and meat quality of heavy pigs. Pigs were divided into five groups receiving 0% (control), 5% or 10% during the growing and finishing phases (42.6-160kg BW) (G+F5,G+F10) or 5% or 10% during the finishing period (100-160kg BW) (FIN5,FIN10) of pure glycerol in substitution for maize meal (on a dry matter basis). The pigs were slaughtered at approximately 160kg BW. The growth performance of pigs fed 5% glycerol did not differ from controls regardless of feeding duration, whereas those fed 10% glycerol showed reduced growth and poorer feed:gain ratio. Fat quality and meat suitability for raw ham curing were not affected by dietary treatment. Differences were not consistent enough to draw any conclusion about the effects of feeding glycerol on sensory characteristics.

Correlation between dietary polyunsaturated fatty acids and plasma homocysteine concentration in vitamin B6-deficient rats.

BACKGROUND AND AIM: Vitamin B6 as cofactor of Delta6 desaturase is involved in polyunsaturated fatty acid metabolism; moreover, it is a cofactor of the trans-sulfuration pathway of homocysteine. Some studies report that low concentrations of pyridoxine, by increasing homocysteine levels, are associated with coronary artery disease, and carotid and arterial lesions. The aim of this study was to verify whether different dietary amounts of polyunsaturated fatty acids associated with low content of vitamin B6 could modulate homocysteinemia. METHODS AND RESULTS: Thirty-two rats were divided into two groups, one fed a diet with adequate vitamin B6 content the other a diet containing low amount of the same vitamin. Within each group, rats were divided into two subgroups differing in the polyunsaturated fatty acid content of the diet (63 and 33%, respectively). The vitamin B6-deficient diet induced an increase in homocysteine concentration compared to the vitamin B6-normal diet. This increase was tenfold in the subgroup fed high polyunsaturated fatty acid levels and twofold in the other subgroup. The fatty acid composition of liver phospholipids showed a lower arachidonic acid relative molar content and a lower 20:4/18:2 ratio in vitamin B6-deficient groups compared with B6-normal groups. CONCLUSIONS: On the basis of the different biological functions of pyridoxine and considering that some factors closely related to atherosclerosis are vitamin B(6) dependent, adequate pyridoxine availability could be necessary to assure a normal long chain fatty acid metabolism and to reduce the risk linked to hyperhomocysteinemia.

Effect of feeding partially hydrogenated lard on trans-fatty acid content of muscle and backfat of heavy pigs.

The incorporation of fat in diets for heavy pigs may be necessary in order to increase their energy intake in the finishing period. Lard may be a good lipid source but it contains 10-13% of linoleic acid, which makes the subcutaneous fat less suitable for long term curing of raw ham. Partial hydrogenation of lard decreases linoleic acid content, but increases trans-fatty acid content. This trial involved two groups of pigs of 114kg live weight, fed for the last two months before slaughter with diets containing 3% lard (L) or 3% partially hydrogenated lard (PHL). The PHL contained about 10% trans-fatty acids and 2.5% linoleic acid. Rearing performance and carcass characteristics were unaffected by treatment. The group fed PHL showed a lower percentage of linoleic acid in the backfat (PHL 12.28% vs. L 13.04%) and a higher percentage of C18:1 trans-fatty acids both in backfat (0.5% vs. 0.06%) and in intramuscular fat (0.2% vs. 0.04%).

Value of buserelin testing in the evaluation of hirsute women.

It has been recently reported that many hirsute women are affected with functional ovarian hyperandrogenism (FOH)-a term that encompasses the heterogeneous polycystic ovary syndrome- and show an abnormal ovarian steroidogenic response to gonadotropin-releasing hormone (Gn-RH) agonists. The aims of the present study were to determine the prevalence of FOH by the assessment of 17-hydroxyprogesterone (17-OHP) response to the Gn-RH agonist buserelin, to correlate these abnormal responses to other parameters suggestive of PCOS, and to assess the possible adrenal origin of hyperandrogenism. Therefore, in 33 consecutive women with hirsutism serum LH, FSH, 17-OHP, dehydroepiandrosterone sulfate (DHEA-S), androstenedione (A), cortisol levels were evaluated in basal conditions and after the administration of buserelin (0.5 mg sc) and ACTH (tetracosactide 0.25 mg iv). Two patients were affected with a non classic congenital adrenal hyperplasia (CAH)-21OH deficiency. In 5 other women ACTH test caused a rate increase 17-OHP (30-0)/30 min > 19 nmol/L/min (0.25 +/- 0.03; mean +/- SE), suggesting the possible existence of heterozygote non classic CAH-21OH. One patient showed a DHEA-S response to ACTH (from 10.3 to 17.2 mumol/L), which was compatible with late-onset 3 beta-Hydroxy-delta 5 steroid dehydrogenase deficiency. Out of the 25 patients with normal responsiveness to ACTH, 11 women (group A) showed higher 17-OHP and A levels, in comparison to normal women, both in basal conditions (17-OHP = 4.18 +/- 0.72 vs 1.74 +/- 0.34 nmol/L, p < 0.005; A = 11.8 +/- 1.2 vs 6.0 +/- 0.7 nmol/L, p < 0.05) and after buserelin (17-OHP = 15.61 +/- 1.31 vs 6.96 +/- 0.9 nmol/L; A = 19.0 +/- 1.9 vs 7.5 +/- 0.8 nmol/L; p < 0.001). In 6 of these 11 patients basal and buserelin-stimulated LH levels were higher than in normals. The remaining 14 patients (group B) showed normal baseline and buserelin-stimulated 17-OHP and A concentrations. In this group only 2 patients had high basal and stimulated LH levels. An augmented LH/FSH ratio was present in 5 and 1 cases of groups A and B, and polycystic ovaries at ultrasonography were observed in 7 and 8 cases of groups A and B, respectively. It is to note that an abnormal 17-OHP response to buserelin was present also in 3 of the 5 patients with abnormal 17-OHP rise after ACTH test, suggesting an adrenal and ovarian cause of hyperandrogenism. In conclusion, an abnormal response to one or both stimulation test was present in 57% of cases: an adrenal origin of hirsutism was detected in 15%, a combined adrenal and ovarian origin was found in 9% and an ovarian cause was present in 33%. Buserelin testing is an useful means to reveal the presence of FOH.

Factors influencing the immediate and late outcome of Cushing's disease treated by transsphenoidal surgery: a retrospective study by the European Cushing's Disease Survey Group.

Hypercortisolism attributable to hypersecretion of ACTH by a pituitary adenoma is an uncommon and progressively lethal disease. Because of its rarity, it has been difficult to collect a large series of patients in order to identify the prognostic factors influencing the outcome after transsphenoidal surgery. We conducted a multicenter, retrospective analysis of the early and late results of surgical treatment of Cushing's disease. Files of patients with Cushing's disease who underwent transsphenoidal surgery between 1975 and 1990 were collected from 25 institutions throughout Europe. Data from 668 of 716 patients were suitable for statistical analyses. Surgical mortality was 1.9%, and major morbidity occurred in 97 patients (14.5%). Clinical and biochemical remission of Cushing's disease after surgery occurred in 510 cases (76.3%). Identification of the tumor by neuroradiological imaging or at operation with histopathological corroboration was associated with remission of hypercortisolism. Recurrence of the disease occurred in 65 (12.7%) of 510 patients in remission after surgery at a mean time of 39.3 months (range 6-104 months). The distribution of the recurrences did not show any apparent plateau or cluster throughout the follow-up period. Low postoperative steroid levels, absence of cortisol response to CRH, and the need for long-term glucocorticoid substitution therapy were all associated with a high probability of long-term remission. Our study demonstrates that transsphenoidal surgery is a safe and effective treatment for patients with Cushing's disease. However, after successful surgery there is a steady increase in the percentage of recurrences, which continues with time. Patients who after operation had hypoadrenocorticism and needed long-term glucocorticoid substitution therapy had the lowest risk of relapse.

Effect of atrial natriuretic factor infusion on basal and CRH-stimulated ACTH, cortisol and aldosterone levels in patients with Cushing's or Addison's disease.

OBJECTIVE: While it has been shown that atrial natriuretic factor (ANF) is able to inhibit CRH-stimulated ACTH secretion in vitro, in normal men conflicting results on its effect on ACTH/cortisol responses to insulin and CRH have been reported. Since no data are available concerning the possible influence of ANF on the hypothalamic-pituitary-adrenal axis in states of ACTH hypersecretion, the effect of ANF on pituitary-adrenal function in basal conditions and after CRH stimulation has been investigated in patients with Cushing's (n = 4) and Addison's disease (n = 4). DESIGN: On two different days all patients underwent the following procedures: (a) alpha-human ANF was infused, after a priming dose of 100 ng i.v., at a rate of 0.01 microgram/kg/min over 5 hours. After 120 minutes of ANF infusion, oCRH (1 microgram/kg) was i.v. injected as a bolus; (b) vehicle infusion was given over 5 hours and at 120 minutes oCRH was injected. Plasma ANF, ACTH, cortisol, aldosterone, renin activity and K+ were measured; heart rate and blood pressure were monitored. RESULTS: In Cushing's disease plasma ANF rapidly increased within 30 minutes of the exogenous peptide infusion (from 27 +/- 5 to 73 +/- 14 pmol/l; mean +/- SE), whereas in the vehicle study its concentration was unchanged. During the first 2 hours of both tests no significant modifications in ACTH levels were observed. After CRH the plasma ACTH peak was unchanged. Serum cortisol levels progressively declined during the first 2 hours of ANF infusion (from 778 +/- 150 to 461 +/- 48 nmol/l; P < 0.05), whereas no changes were observed during vehicle. After CRH serum cortisol rose to similar peaks. Plasma aldosterone levels were significantly reduced during the first 2 hours of ANF infusion (from 81 +/- 20 to 35 +/- 7 pmol/l P < 0.05), whereas no changes were found during vehicle. A similar aldosterone rise was induced by CRH during either vehicle or ANF. Mean plasma renin activity slightly declined and the changes were similar on both occasions. In Addison's disease ANF levels rose within 30 minutes of the peptide infusion (from 12 +/- 1 to 49 +/- 8 pmol/l), while they were unchanged during vehicle. A slight decline in ACTH levels in the first 2 hours was observed during either vehicle or ANF infusion. After CRH the plasma ACTH peaks were similar. Mean plasma renin activity was unaffected by vehicle, while ANF caused a decline during the first 2 hours (from 13.4 +/- 0.8 to 7.7 +/- 0.3 ng/ml/h). In all patients, heart rate, blood pressure and K+ were only slightly affected on both occasions. CONCLUSIONS: (1) In patients with corticotrophin hypersecretion ANF does not influence basal and CRH-stimulated ACTH secretion; (2) in Cushing's disease ANF inhibits cortisol and aldosterone basal secretion; this effect is not mediated by ACTH and is over-ridden by CRH stimulation.

Accuracy of self-assessment of the minimal record of disability in patients with multiple sclerosis.

We tested the validity of a self-administered version of the minimal record of disability (MRD) for multiple sclerosis (MS) by measuring the agreement level between patients' self-assessment and neurologists' independent ratings. 96 MS patients and 4 neurologists took part in the experiment; the agreement level was measured in terms of the intraclass correlation coefficient (ICC). On the Kurtzke functional system (FS) the ICC ranged from 0.26 in the sensory to 0.69 in the pyramidal function; a high concordance (ICC = 0.84) was found on the expanded disability status scale (EDSS). The ICC values were above 0.70 for most of the incapacity status scale (ISS) and environmental status scale (ESS) items. A modified, self-administered version of the MRD may represent a reliable instrument for obtaining a comprehensive profile of patients' abilities.